2-substituted benzimidazoles and their use in the inhibition of echo 6 and poliomyelitis



United States Patent Z-SUBSTITUTED BENZIMIDAZDLES AND THEIR USE IN THE INHIBITION OF ECHO 6 AND POLIOMYELITIS Arthur F. Wagner, Princeton, and Karl A. Folkers, Plainfield, N.J., assignors to Merck & Co., Inc., Rahway, N..I., a corporation of New Jersey No Drawing. Filed Nov. 1, 1961, Ser. No. 149,214

10 Claims. (Cl. 16765) This invention relates to new compounds useful in the inhibition of poliomyelitis viruses and to compositions comprising said compounds for the inhibition of the growth of said viruses. More specifically, this invention relates to a compound of the structure N U i i'@ OH in which X and Y may be hydrogen or lower alkyl, at least one of them being lower alkyl, and to compositions comprising such compounds as an active ingredient for inhibiting the growth of poliomyelitis and ECHO 6 viruses.

Science is beginning to secure control of poliomyelitis by means of immunization vaccines. There is, however, another approach to the control of this disease and especially the spread of its viruses. This is to find compounds capable of inhibiting the growth of the viruses and of preventing cell damage therefrom.

We have found that 2-[a-hydroxybenzyl]benzimidazoles which are substituted with alkyl groups are more potent inhibitors of poliomyelitis and ECHO 6 virus than previously known compounds. These viruses are members of the class of enteroviruses, the member of which resemble one another in their reaction to these compounds, among many similar properties. We have found that alkyl groups on either the tat-position of the benzyl moiety or on N of the benzimidazole, ring enhance the inhibitory activity.

No representation is made herein as to the suitability or unsuitability of the compounds of this invention for the treatment of humans.

In the preparation of the compounds of this invention, alkyl groups are introduced at N of the benzimidazole ring by starting with an o-amino-N-alkyl-aniline such as o-amino-N-methyl-, ethyl-, propyl-, or butylaniline. These compounds are reacted with mandelic acid in dilute acid solution. A suitable acid is 4 N-hydrochloric acid. The product of this reaction is a l-lower alkyl Z-(Ot-hYdI'OXY- benzyl) benzimidazole. Such compounds can be alkylated by oxidizing the l-lower alkyl 2 [on hydroxybenzyl] benzimidazole, e.g., with dichromate, to the corresponding Z-benzoylbenzimidazole. This product can then be dissolved in ether and added to an ether solution of a lower alkyl Grignard reagent to form 2-(w-lower alkyl-ahydroxybenzyl)benzimidazo1e having a l-alkyl group. The latter method can also be used to prepare the compounds of this invention having only on a-alkyl-a-hydroxybenzyl substituent. The starting material in this case is 2-benzoylbenzimidazole.

The compounds of this invention are tested for their inhibitory powers on viruses in the following manner:

Tissue cultures of monkey kidney cells in protein-free Eagles medium (Eagle, J. Ex. Med., 102, 595 (1955)) are used to evaluate the compound for the inhibition of virus multiplication. About six cultures are used per variable and the innoculum of virus is 500 times the 50%tissue culture infective dose. The infected cells are treated with varying concentrations of a given compound and the cultures are examined at 3-day and 6-day intervals for the extent of cell damage. The concentration of a compound 3,331,739 Patented July 18, 1967 which would afiord a 75% protection from cell damage is designated the protective concentration. Experimentally, this data is found to cor-relate with the inhibition of the multiplication of the virus as found by direct measure- 5 ment and consequently is a good measure of that as well. The relative results of some of the compounds of this invention with respect to the best previous compounds, 2-[a-hydroxybenzyl]benzimidazole, in protection against ECHO 6 virus are as follows: 10 Relative inhibition 2 (a hydroxybenzyl) benzimidazole 1.0

1-methyl-2-(u-methyl a hydroxybenzyl)benzimidazole 4.8 2-(a-methyl a hydroxybenzyl)benzimidazole 2.9 2-(oz-ethyl a hydroxybenzyDbenzimidazole 2.7

Our invention can be illustrated by the following examples:

Example 1 N Five grams (.023 mole) of 2-benzoylbenzimidazole in 300 ml. of ether is added to a solution of 0.125 mole of methyl magnesium iodide in 150 ml. of ether. The reaction mixture is acidified with ml. of 25% sulfuric acid, 30 and 150 ml. of water is added. The ether phase is washed with water and the combined aqueous phases are cooled and neutralized with concentrated ammonium hydroxide. The product which precipitates is isolated by ether extraction. The combined ether extracts are dried over sodium sulfate and concentrated to give a residue which is crystallized from ethanol-water, yielding Z-(a-methyI-uhydroxybenzyl)benzimidazole, M.P. ISO-181.

Analysis.Calcd. for C H N O: C, 75.60; H, 5.92; N, 11.76. Found: C, 75.03; 75.67; H, 6.06; 5.69; N, 12.57, 10.53.

Example 2 Example 3 N CH3 /CH3 OH i H Five grams (.023 mole) of 2-benzoylbenzimidazole in 500 ml. of ether is added to a solution of 0.125 mole of isopropyl magnesium iodide in ml. of ether. The re action mixture is acidified with 25 sulfuric acid and Example 4 N (EH.

A mixture of 7.98 g. (.066 mole) of 2-amino-N-methyl aniline, 14.95 g. (.098 mole) of mandelic acid and 50 ml. of 4 N HCl is refluxed for one hour. The reaction mixture is cooled and treated with ammonium hydroxide. The product precipitates, and is collected by filtration and washed with water. The product is dissolved in 75 ml. of hot ethanol and the solution is treated with activated charcoal and then filtered. The filtrate is diluted with 50 ml. of water and then warmed. When the solution is cooled, the product crystallizes and is collected by filtration. The product is dissolved in ethanol, treated once again with charcoal and thencrystallized to yield 5.9 g. of 1 methyl 2 (a-hydroxybenzyl)benzimidazole, M.P. 155-157". V

Analysis.--Calcd. for C H N O: C, 75.60; H, 5.92; N, 11.76. Found: C, 76.40; H, 6.18; N, 11.34.

A second crop of product is obtained by diluting the mother liquors with 75 ml. of water to yield 2.4 g. of 1-methyl-2-(oi-hydroxybenzyl)benzimidazole, M.P. 158- 160.

Analysis.Found: C, 75.48; H, 5.65; N, 11.61.

When 2 amino N ethylaniline, 2 amino-N-propylaniline, or Z-amino-N-butylaniline is used in the above example, in place of Z-amino-N-methylaniline, in equivalent quantities, the correspondingly substituted l-lower alkylbenz'unidazole compound is obtained.

Example 5 Five hundred mg. of 2-(a-methyl-a-hydroxybenzyl) benzimidazole is dissolved in 15 ml. of acetone. Two grams of anhydrous potassium carbonate and 0.29 g. of methyl iodide are added to the solution. The reaction vessel is' stoppered and the mixture is stirred overnight at room temperature. The mixture is filtered, and the filtrate is concentrated in vacuo. The residue is crystallized from 50 ml. of 50% aqueous ethanol to yield 390 mg. of 1 methyl 2 (a methyl a hydroxybenzyl)benzimidazole, M.P. 191-3".

Analysis.Calcd. for C H N O: C, 76.16; H, 6.39; N, 11.10. Found: C, 75.96; H, 6.19; N, 11.10.

We claim:

1. A compound of the structure in which X and Y are each selected from the group consisting of hydrogen and lower alkyl, at least one of X and Y being lower alkyl.

2. 2-(oi-methyl-a-hydroxybenzyl)benzimidazole.

3. 1-methyl-2-(a-methyl a hydroxybenzyl)benzimidazole.

4. 2-(ot-ethyl-a-hydroxybenzyl)benzimidazole.

5. 1-methyl-2-(a-hydroxybenzyl)benzimidazole.

6. A method for inhibiting the growth of ECHO 6 and poliomyelitis viruses which comprises applying to cells infected with such virus a composition having as an active ingredient a compound of the structure *EQ OH X in which X and Y are each selected from the group consisting of hydrogen and lower alkyl, at least one of X and Y being lower alkyl.

7. The method of claim 6 in which the compound is 2-(a-methyl-u-hydroxybenzyl)benzimidazole.

8. The method of claim 6 in which the compound is V 1-methyl-2-(a-methyl-a-hydroxybenzyl)benzimidazole.

9. The method of claim 6 in which the compound is 2- ot-ethyl-a-hydroxybenzyl) benzimidazole.

10. The method of claim 6 in which the compound is 1-methyl-2-( a-hydroxybenzyl) benzimidazole.

References Cited WALTER A. MODANCE, Primary Examiner.

D. T. McCUTCHEN, N. S. RIZZO, Examiners.

N. TROUSOF, Assistant Examiner. 

1. A COMPOUND OF THE STRUCTURE
 6. A METHOD FOR INHIBITING THE GROWTH OF ECHO 6 AND POLIOMYELITIS VIRUSES WHICH COMPRISES APPLYING TO CELLS INFECTED WITH SUCH VIRUS A COMPOSITION HAVING AS AN ACTIVE INGREDIENT A COMPOUND OF THE STRUCTURE 